Reference is made to my above-identified copending patent application for further background of this invention. As previously pointed out in Ser. No. 490,210, it is advantageous to coat the outer peripheral surface of a string of sucker rod with a suitable coating which acts as a barrier to the deleterious environment found downhole in a borehole. Various different geographical locations present various different problems respective to chemical attack upon the metal composition of the sucker rod. In pumping wellbores, the sucker rod is usually placed in intimate contact with H.sub.2 S, H.sub.2 O, free hydrogen ions, and various other harmful chemicals.
These chemicals may either catalyze the oxidation process of the metal sucker rod, or they may directly enter into various chemical reactions with the metal composition of the rod. It is therefore desirable to be able to protect the sucker rod by applying a coating which provides a barrier between the main metal body of the rod and the deleterious effects of the downhole fluids.
It is desirable to provide a wellbore with sucker rod which is absolutely reliable in structural integrity and which furthermore can withstand the onslaught of the various chemicals found downhole in a borehole.
A string of sucker rods having these desirable attributes will last indefinitely and therefore avoid replacement over a long period of time. Reliability of this magnitude has not heretofore been attained and would represent a substantial savings in the cost of producing hydrocarbons. The present invention therefore has the unexpected advantage of longer life and therefore significantly reduces the cost of producing well bores.